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Coaching Materials in Digital and Data Communications Part 1 for ECE Board Exam

Compiled coaching materials in Digital and Data Communications Part 1 as one topic in ECE Board Exam taken from different sources including but not limited to Communications books, past Board Exams Questions, Journals and the Internet.

This is the Coaching materials in Digital and Data Communications Part 1 as one topic in ECE Board Exam taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies (EST), Communications Books, Journals and other Communications References. This particular Coaching Notes in Communications Engineering has random Questions and Answers in random topics. Make sure to familiarize this review notes to increase the chance of passing the ECE Board Exam.

Digital and Data Communications Coaching Materials Part 1

1. The first digital code was the:

Morse code

2. Advantage of digital over analog transmission.

Noise immunity

3. Hartley’s Law is:

I = ktB

4. The Shannon-Hartley theorem is:

C = 2Blog(2M)

5. The Shannon Limit is given by:

C = B log2 (1 + S/N)

6. In North America, companding uses:

the m Law (mu law)

7. A typical codec in a telephone system sends and receives:

8-bit numbers

8. In delta modulation, “granular noise” is produced when:

the signal does not change

9. Which coding scheme requires DC continuity:

unipolar NRZ

10. Number of independent symbols that can be propagated out through a communications system which is a function of bandwidth.

Information capacity

11. Refers to the rate of change of a signal on a transmission medium after encoding and modulation have occurred.

Baud rate

12. What is the relationship of bit rate and baud in FSK and PSK?

Equal

13. What is the relationship of bit rate and baud in QPSK and 8-PSK?

Bit rate is greater than baud

14. A digital modulation technique also known as “on-off” keying.

Amplitude Shift Keying or ASK

15. From of digital modulation using its modulation signal (a binary pulse stream) that varies between two discrete voltage levels.

FSK

16. In FSK, a figure of merit used to express the degree of modulation.

H-factor

17. Most common modulation technique used for radio telegraphy.

FSK

18. It is a type of FSK where the mark and space frequencies are synchronized with the input binary rate.

Continuous-Phase Frequency-Shift Keying or CPFSK

19. The most common circuit used for demodulating binary FSK signals.

Phase locked loop

20. A form of digital modulation similar to PSK except the digital information is contained in both the amplitude and the phase of the transmitted carrier.

Quadrature Amplitude Modulation

21. If is often used to compare the performance of one digital modulation technique to another

Bandwidth efficiency, Information density of Spectral efficiency

22. It is the ratio of the transmission bit rate to the minimum bandwidth required for a particular modulation scheme.

Bandwidth efficiency, Information density of Spectral efficiency

23. For an 8-PSK system, operating with an information bit rate of 24 kbps, determine the bandwidth efficiency.

3 bits/cycle

24. For a 16-PSK and a transmission system with a 10 kHz bandwidth, determine the maximum bit rate.

40,000 bps

25. A common method of achieving carrier recovery for BPSK.

Squaring loop

26. A modulation technique where data rates I excess of 56 kbps can be achieved over telephone circuits.

Trellis code modulation

27. It is a theoretical expectation of the bit error rate in the system.

Probability of errors

28. It is a function of the carrier-to-noise power ratio and the number of possible encoding conditions used.

Probability of error

29. It is the ratio of the average carrier power to the thermal noise power.

Carrier-to-noise ratio

30. It is the thermal noise power normalized to 1-Hz bandwidth.

Noise power density

31. It is used to compare two or more digital modulation systems that use different transmission rates, modulation scheme or encoding techniques.

Energy per bit-to-noise power density ratio

32. The phase relationship between signaling elements for BPSK is the optimum signaling form and occurs only when two binary signal levels are allowed and when one signal is the exact negative of the other.

Antipodal signaling

33. An “eye pattern” shows a good channel when:

the eye is maximally open

34. What you see in an eye pattern is the effect of:

intersymbol interference

35. High-frequency radioteletype systems commonly use:

FSK

36. In digital modulation, such as FSK, the rate of change of frequency at the input is called